Barn Second Floor with Vaulted Ceiling

[Mczook]

The barn is 60' x 32', has two floors  I've created the first floor, with windows and doors.  The second floor is actually two lofts at each end of the barn that is separated by an open, each loft measures 20'x32'. The open that separates the two lofts, exposing the first floor, is also 20'x32'.  I created the lofts using the block tool.  My issue is how to create walls for the loft.  It's a vaulted barn ceiling.  Side walls are shorter than end walls.  I see when I put on a pitched roof, walls fill in automatically the peaked end.  My problem is that I'm unable to put windows on those walls.  How do you create a room with different sized walls, with an angled ceiling, one that you can place windows.  Thank you.